Aerating liquid discharge nozzles

ABSTRACT

A family of aerating liquid discharge nozzles, each of which has the feature that it contains no moving parts and includes a hollow body defining a liquid inlet at one end and an outlet opening at the other end. The body has an internal chamber arranged in communication with both the inlet and outlet ends of the body. A plug, having substantial length between opposite end surfaces, is disposed across the chamber adjacent the body outlet end and defines constricted liquid outlet means from the body. The body outlet opening has an area greater than the area of the liquid outlet means defined by the plug.

United States Patent lnventor John O. Hruby, Jr.

Burbank, Calif.

Appl. No. 784,541

Filed Dec. 9, 1968 Patented Jan. 26, 1971 Assignee Rain Jet Corporation Burbank, Calif. a corporation of California Continuation-in-part of application Ser. No. 691,111, Dec. 8, 1967, now abandoned which is a continuation-in-part of application Ser. No. 492,389, Oct. 4, 1965, now abandoned.

AERATING LIQUID DISCHARGE NOZZLES 12 Claims, 18 Drawing Figs.

Primary Examinerl.loyd L. King Attorney-Christie, Parker & Hale ABSTRACT: A family of aerating liquid discharge nozzles, each of which has the feature that it contains no moving parts and includes a hollow body defining a liquid inlet at one end and an outlet opening at the other end. The body has an internal chamber arranged in communication with both the inlet and outlet ends of the body. A plug, having substantial length between opposite end surfaces, is disposed across the chamber adjacent the body outlet end and defines constricted liquid outlet means from the body. The body outlet opening has an area greater than the area of the liquid outlet means defined by the plug.

INVENTOR.

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PATENTED mes lsn SHEET 2 [)F 4 PATENTEDJANZBIQH 3.658.053

SHEET 3 OF 4 INVENTOR. L/i/V/V d Hal/5K AERATING LIQUID DISCHARGE NOZZLES CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of copending application Ser. No. 69l,l l I filed Dec. 8, 1967, now abandoned, as a continuation-in-part of Ser. No. 492,389 filed Oct. 4, I965, now abandoned.

BACKGROUND OF THE INVENTION 1. 1. Field of the Invention This invention relates to liquid handling and, more particularly, to nozzles for discharging aerated liquid in a predetermined pattern. Nozzles according to this invention are characterized by the absence of moving parts in the liquid stream.

2. Description of the Prior Art In ornamental fountain arrangements which are to be viewed during the day without illumination by artificial light, it is desired that the discharged water he aerated as fully as possible in order that the water discharge pattern may be readily visible. Aerating fountain heads or nozzles are known. Present fountain heads, however, produce only a limited number of water discharge patterns. Many existing aerating fountain heads do not produce sufficient aeration of the water discharged from them. Moreover, many existing aerating nozzles contain moving parts which wear as the nozzle is operated. In other cases, existing aerating nozzles require critical clearances in the noule openings to produce the desired aeration; these clearances either become worn by erosion as the nozzle is operated, or clogged by foreign particles in the liquid passing through the nozzle head, thus adversely affecting the nozzle aerating efficiency.

For efficiency of operation, an aerating fountain nozzle should produce the appearance of discharging a massive stream of water even though the quantity of water actually passed through the nozzle is relatively moderate. When this desired condition is obtained, a small pump may be used, thus resulting in a fountain which is economical to operate. Also, in order that they may be used in populated areas, aerating fountain nozzles should produce as little mist or fine spray as possible; mist is readily transported by slight breeze out of the fountain area to locations where viewers may be positioned. Mist also tends to mask the basic fountain discharge pattern and thus detracts from the aesthetic efi ect desired in the fountain.

The design of aerating liquid nozzles is often more of an art than a science, especially where it is desired that the aerated liquid discharged from the nozzle follow a redetermined path from the nozzle throughout a relatively wide range of liquid pressures applied to the nozzle, and where the discharge is to be used to produce an ornamental effect. The use of techniques and principles which are effective in gas mixing nozzles, wherein two or more gases are mixed in the nozzle structure and are discharged as a mixture, is practical in only random situations in aerating liquid nozzles because of the widely different physical properties between gases and liquids.

SUMMARY OF THE INVENTION This invention provides a simple, rugged, efi'ective and efficient aerating nozzle which is particularly useful in omamental fountain arrangements. The nozzle contains no moving parts which may wear as the nozzle is operated. Moreover, no critically sized apertures are provided in the nozzle, and thus water erosion and the presence of foreign particles in the water passed through the nozzle have little effect, if any, upon the aerating efiiciency of the nozzle. The nozzle produces the appearance of a massive discharge stream even though the actual volume of water passed therethrough is moderate. Moreover, nozzles according to this invention provide diverse and novel liquid discharge patterns which are essentially free of objectionable mist or fine spray and which are readily visible because of the high degree of aeration of the nozzle discharge and freedom from mist.

Generally speaking, this invention provides an aerating liquid discharge noule which includes an elongate straight body defining a duct between a liquid inlet and an liquid outlet opening located across opposite ends of the body. A plug, having substantial length between its opposite end surfaces relative to the diameter of the duct, is disposed across the duct adjacent the duct outlet opening. The duct inlet opening has an area which is at least as great as the effective crosssectional area of the duct at the location of the plug along the duct. The plug defines liquid passage means through it, such passage means being comprised of a plurality of grooves formed in the plug sidewalls at spaced locations around the circumference of the plug. Each groove communicates between the opposite ends of the plug. The passage means has a cross-sectional area, at least adjacent the other end of the body, which is substantially less than the cross-sectional area of the duct through the portion of the duct in which the plug is disposed. The grooves are configured so that the boundary surfaces thereof defined by the plug intersect at a substantial angle, the groove boundary surfaces defined by the walls of the duct. The plug sidewalls between adjacent grooves are engaged in surface-to surface contract with the duct walls, and preferably, adjacent extremities of adjacent grooves are spaced circumferentially of the plug a distance at least equal to the width of one of the grooves. A line between corresponding locations of opposite ends of each groove is skew, within an angle of from 0 to about 30, to the length of the plug, and the ends of the grooves at one end of the plug are spaced apart relative to each other according to substantially the same pattern as are the ends of the grooves at the other end of the plug. The surface of the plug adjacent to the other end of the body around the opening of each of the grooves to such surface is substantially normal to the length of the plug.

BRIEF DESCRIPTION OF THE DRAWINGS The above-mentioned and other features of the present invention are more fully set forth in the following detailed description of the invention, the description being presented in conjunction with the accompanying drawings, wherein:

FIG. I is a cross-sectional elevation view of an aerating liquid discharge nozzle according to this invention;

FIG. 2 is a top plan view taken along lines 2-2 of FIG. 1;

FIG. 3 is a cross-sectional plan view taken along lines 31 33 of FIG. 1;

FIG. 4 is an elevation view of the water discharge pattern produced by the nozzle shown in FIG. 1;

FIG. 5 is a fragmentary cross-sectional elevation view of another nozzle similar to the nozzle shown in FIG. 1.

FIG. 6 is a cross-sectional elevation view of another nozzle according to this invention;

FIG. 7 is a top plan view of the nozzle shown in FIG. 6;

FIG. 8 is cross-sectional elevation view taken along lines 8-8 of FIG. 6;

FIG. 9 is an elevation view of the liquid discharge pattern produced by the nozzle shown in FIG. 6;

FIG. 10 is an elevation view of the liquid discharge pattern produced by a modification of the nozzle shown in FIG. 6;

FIG. 1 l is a cross-sectional elevation view of another nozzle according to this invention;

FIG. 12 is an elevation view of the liquid discharge pattern produced by the nozzle shown in FIG. 11:

FIG. I3 is a cross-sectional elevation view of another nozzle according to this invention;

FIG. 14 is an elevation view of the liquid discharge pattern produced by the nozzle shown in FIG. 13;

FIG. 15 is a cross-sectional elevation view of another nozzle according to this invention;

FIG. 16 is an elevation view of the water discharge pattern which may be produced by the nozzle shown in FIG. 15;

FIG. 17 is an elevation view of the nozzle shown in FIG. 15 mounted on an angle to the vertical and showing a discharge pattern which may be produced by the nozzle; and

FIG. 18 is a cross-sectional elevation view of another nozzle according to this invention.

The several nozzles shown in the drawings are described with relation to one another in order that the following description may be made without unnecessary repetition. Workers skilled in the art to which this invention pertains will readily recognize that the features and constructional details encountered in one described nozzle may be incorporated within a different described nozzle without departing from the teachings of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An aerating liquid discharge nozzle I0, which is particularly useful in ornamental fountains and shown in FIG. 1, includes an elongate, hollow, tubular body II defining an elongate, circularly cylindrical ductlike internal chamber 12. The body has an internally threaded open lower end 13 to adapt the body to be securely connected to a suitably sized water discharge pipe or the like (commonly known as a riser pipe) through which water at suitable pressure is supplied to the nozzle. The lower end of the body defines a liquid inlet opening to chamber 12. The cylinder defined by the inner wall of the body is open across its entire extent at an open upper end 14 of the body. A plug 15 having substantial thickness, relative to the inner diameter of the body, between opposite parallel and preferably planar end surfaces 16 and 17 is disposed across the interior of the body adjacent the upper end of the body. A water outlet passage 18 is formed through the plug axially of the body and has a cross-sectional area substantially less than the cross-sectional area of chamber 12. In nozzle 10, as in all nonles according to this invention, the area of the liquid inlet opening to the nozzle is at least as great, and preferably greater than, the area of the liquid flow passage through the plug. The passage has substantially equal areas at all locations along its length between the end surfaces of the plug. As with the other nozzles described hereinafter, nozzle is devoid of any structure spanning the duct downstream of plug 15. That is, after water passes plug 15, it does not pass through any additional structure, other than the body itself, in emerging from the nozzle.

As shown best in FIG. 2, passage 18 is defined by a combination of a circularly cylindrical opening 19 formed through the plug axially of the body and by a plurality of substantially identical semicircular grooves or flutes 20 which open concave to opening 19 along the entire length of the plug; the grooves open to the opposite end surfaces of the plug. Preferably, as shown in FIG. 2, the grooves are spaced apart form each other around the circumference of opening 19 at a distance greater than the diameter of the grooves. Accordingly, a generally square ended rib 21 is defined between each adjacent pair of grooves. Thus, the grooves are distinctly spaced from each other around the central opening through the plug and the generation of thin sheets of water is avoided in the discharge pattern of nozzle 10. It has been found that the presence of thin sheets of water in the discharge pattern degenerate remote from the head into mist or fine spray which is objectionable for the reasons set forth above.

A hollow cylindrical tube 23 extends axially into chamber 12 away from plug toward the inlet opening to chamber I2. The tube is disposed concentric to the axis of the body and has a closed end 24 spaced away from the plug. The interior of the tube defines a circularly cylindrical chamber 25. The outer diameter of the tube is substantially less then than the inner diameter of the body so that, along the length of the tube, chamber 12 has an annular configuration. In nozzle I0 the tube has an upper end 26 abutted against plug lower end surface 17. A plurality of slots 27, elongated in the direction of the length of the tube and spaced apart around the circumference of the tube, extend through the sidewalls of the tube to provide the sole communication between chambers 12 and 25. The slots, as shown in FIG. 3, extend from the exterior of the tube into substantial tangency with the circularly cylindrical inner walls of the tube. All of the slots communicate with the interior of the chamber in the same angular sense, i.e., all

the slots are angled either clockwise or counterclockwise to the tube. The tube is mounted in an axial bore 28 of an annular ring 29 which is disposed across the interior ofthe body immediately below plug I5. An O-ring 30 is engaged between ring 29 and the body to prevent liquid from leaking between the ring and the body. Accordingly, water flow through the nozzle is solely along a path through the open lower end of the body into chamber 12, through slots 27 into chamber 25, spirally around and upwardly along the inner surfaces of tube 23, and through outlet opening 18 to the exterior of the nozzlev In small nozzles 10, it is preferred that the inner diameter of tube 23 be greater than the diameter of hole 19, but less than the diameter of passage 18 as measured across the portions of the grooves spaced farthest from the axis of the noule, for best aeration of water passed through the nozzle. In larger nozzles 10, however, it is preferred that the diameter of hole 19 be greater than the inner diameter of tube 23. For example, in the nominal 29% inch nozzle described in detail below, hole 19 is smaller than the cross-sectional area of tube 23. In a nominal 4 inch nozzle, however, where the tube may have an inner diameter of 2 5/16 inches, hole 19 preferably has a diameter of 2% inches. It is also preferred that the plug between opposite end surfaces I6 and 17 be substantially equal to the maximum transverse dimension of the passage through the plug.

FIG. 4 shows nozzle 10 and a water discharge plume or pattern 31 produced by such a nozzle when water is supplied under pressure to the nozzle. When the nozzle is vertically oriented, the discharge plume has a symmetrical conical configuration. The nozzle discharge is readily visible in daylight from a considerable distance since the water which forms the discharge plume is highly aerated. The discharge pattern is remarkably free of mist which might mask the basic pattern or which might, in a breeze, wet nearby observers of the fountam.

As water enters into chamber 25 from chamber 12 through angularly oriented slots 27, this water is caused to flow spirally around and upwardly along the surfaces of tube 23 and is believed to form a vortex into which is drawn air from the exterior of the nozzle. As the spirally flowing water emerges from tube 23, it encounters ribs 21 which abruptly turn the water emerging from the tube into grooves 20 and cause the water to be thoroughly mixed with air dawn into the vortex. As the water emerges from the upper end of passage 18, it passes over the substantially right-angled shoulder defined by the intersection of plug upper surface 16 with the vertical walls of the outlet opening. Accordingly, the water emerging from the plug separates cleanly from the plug and does not tend to flow along the upper surface of the plug as might be the case were the walls of passage 18 faired into the upper surface of the plug. The is that discharge plume 31 contains a minimum amount of mist or fog over a wide range of applied water pressures and flow rates.

FIG. 5 illustrates a noule 35 which is similar to nozzle 10, except that nozzle 35 includes a plug 26 spaced above the upper end of tube 23 adjacent the open upper end of body I1. Accordingly, a circularly cylindrical chamber 37 is provided between plug 35 and ring 29. Chambers 12 and 37 have equal diameters. Also, plug 36 has a circularly cylindrical passage 38 formed axially through it between opposite parallel plug end surfaces 39 and 40; no grooves, such as grooves 20 of nozzle I0, open to passage 38. Passage 38 defines the liquid outlet opening from nozzle 35. As noted above, for best aeration the diameter of passage 38 can be slightly less than, equal to, or greater than the inner diameter of tube 23. Preferably, the distance between the end surfaces of the plug is substantially equal to at least the diameter of the hole defining passage 38. Nozzle 35 produces a liquid discharge plume substantially identical to plume 31 produced by nozzle 10 and is characterized by the same absence of mist or fog as is encountered in nozzle 10.

It is preferred that the upper end surface of plugs I5 and 36 be coextensive with the upper end of the tubular body within which the plug is mounted. In the event, however, that either one of plugs or 36 is spaced below the open upper end of the body, as shown in FIGS. 1 and 5, care should be taken to locate the plug sufficiently close to the upper end of the body that the water emerging from the plug outlet passage does not interact with the rim of the body at its extreme upper end. Such interaction of the water emerging from the plug outlet passage with the upper end of the body produces a mist or fog and degrades the clean profile of the nozzle discharge plume.

A nozzle 10 having a diameter of chamber I2 of 2 5/l6 inches, a diameter of chamber of 1% inches, a plug length of 2 inches defining an outlet passage consisting of a circular hole of IVs inches diameter in combination with 6 grooves having a radius of A inch formed in the walls of the 1% inch hole has been successfully operated over a wide range of applied water pressures to produce a water discharge plume 31 as shown in FIG. 4. When 80 gallons of water per minute are passed through the nozzle, the discharge pattern produced by the nozzle is ll feet high and 14 feet in diameter; the nozzle head loss or back pressure is only 10 pounds per square inch.

In nozzles 10 and 35, it is preferred that body 11, tube 23 and plugs 15 and 36 be fabricated of polyvinyl chloride. Such a material is resistant to erosion by water flowing through the nozzle at high pressures.

A nozzle 45, as shown in FIG. 6, includes a body 46 which defines a circularly cylindrical interior chamber 47. Chamber 47 opens across its entire diameter to the exterior of the nozzle at an upper end 48 of the body. The body also has a lower end which is not shown but is threaded internally for connection to a water pipe or the like (in this respect, see FIG. 1). The lower end of the body defines a liquid inlet opening to chamber 47. Preferably, body 46 is fabricated of a length of polyvinyl chloride pipe, although it is within the scope of this invention that other materials may be used, or that the body may be fabricated of something other than a length of pipe. In any event, chamber 47 extends without restriction from the open upper end of the body for a substantial distance along the length of the body towards and preferably to the liquid inlet opening to the duct which extends through the body.

A plug 49 having opposite parallel end surfaces 50 and 51 is disposed transversely across the interior of the body at a location on the body spaced below the open upper end of the body. The plug is engaged around its periphery in surface-tosurface contact with the inner walls of the body. The sole communication between chamber 47 below the plug and the exterior of nozzle 45 is provided by a plurality of grooves 52 which are formed in the circumference of the plug. The grooves extend along the entire length of the plug generally parallel to the length of the plug; that is, the grooves, if not precisely parallel to the length of the plug, are more nearly parallel than normal to the length of the plug. The grooves cooperate to define water flow passage means through the plug.

FIG. 6 shows that in nozzle 45 the grooves formed in the sidewalls of plug 49 are skew to the length of the plug, the extent of the angle of skew being represented by a in FIG. 6. The angle of skew of the grooves relative to the length of the plug may be as much as about or so, but not more than above which value the grooves are more normal to the length of the plug rather than generally parallel to the length of the plug. It is within the scope of this invention, however, that a noule having the basic structure of nozzle 45 (hollow, open ended by body and a peripherally grooved plug disposed within the body) may have plug grooves aligned truly or precisely parallel to the length of the plug, as in nozzle 55 shown in FIG. 10. Thus, the invention, relative to nozzles hav ing the basic structure of nozzle 45, comprehends a value of angle a lying in the range of from 0 to about 30 or so.

As shown in FIG. 7, grooves 52 are of semicircular configuration and are closed substantially across their diameters by the inner walls of the body so that the walls of the grooves as defined by plug 49 make a substantial angle (approximately in the case of the structure shown in FIGS. 6 and 7, not withstanding that thegrooves are skew to the length of the plug) with the inner walls of the body. That is, the open crosssectional configuration of grooves 52 is slightly greater than an exact half circle and the diameter of the grooves is substantially less than the diameter of body 46 with the result that the walls of the grooves at the point of intersection thereof with the inner walls of body 46 lie at approximately 90 to the inner walls of the body. Because the value of angle a is within a range of from zero to 30 or so, this nearly right angle relationship between the inner walls of the body and the walls of grooves 52 at the periphery of plug 59 is not significantly modified by virtue of the deviation of the length of the grooves out of exact parallelism to the length of the body. The existence of a substantial angle between the plug-defined groove walls and the body-defined groove walls prevents the generation of mist producing thin sheets of water in the discharge pattern of the nozzle.

Grooves 52 are uniformly spaced apart from each other around the circumference of the plug. Preferably grooves 52 are arranged so that corresponding locations of adjacent grooves, as shown in FIG. 7, are spaced circumferentially of the plug, of one of the grooves. As shown in FIG. 7, each groove 52 has a greater cross-sectional area at plug end surface 51 than at plug end surface 50. In other words, the crosssectional areas of each of grooves 52 decrease uniformly proceeding upwardly along the length of the plug. It is thus seen that the grooves are tapered, the amount of the taper being indicated in FIG. 8 by dimension T.

As shown in FIGS. 6 and 7 where angle a has a finite value, the upperends of the grooves are displaced uniformly angularly in the same direction about the axis of the nozzle relative to the lower ends of the groove. Thus, the upper ends of grooves 52 define essentially the same pattern in the upper surface of the plug as the lower ends of the grooves define in the lower surface of the plug. Stated in another way, if the peripheral surface of the plug were developed i onto a planar surface, it would be found that grooves 52 lie parallel to each other.

Still with reference to FIGS. 6 and 7, the combined crosssectional areas of the grooves at plug end surface 50 is no greater than and preferably is substantially less than the crosssectional area of chamber 47 below the plug and at the liquid inlet opening to the nozzle. Preferably, the plug has a thickness equal to at least about one-half the mean transverse dimension of chamber 47 at the location of the plug across the chamber. Also, each groove 52 should have a length at least twice as long as the mean depth of the groove. As in nozzles 10 and 35, the upper surface of the plug peripherally of the opening of each groove to such surface is substantially normal to the elongate extent of the plug so that the water stream emerging from each groove separates cleanly, without the generation of mist, fog or fine spray, from the plug. Also, the upper end of body 46 should form a sharply defined shoulder with the inner walls of the body so that the generation of mist or fog in the discharge of the nozzle is avoided at this location of the nozzle structure.

FIG. 9 shows a water discharge plume 53 provided by nozzle 45 when the nozzle is connected to a source of water under pressure and water is passed through the nozzle. Plume 53 has an inverted conical configuration similar to plume 31 provided by nozzle 10. Plume 53, however, is defined by a series of distinct and readily identifiable jets 54 of aerated water, there being the same number of jets as there are tapered and angled grooves in plug 49. The ratio of cone height to cone diameter is determined principally by the value of angle a.

To produce discharge plume 53, it is preferred that plug 49 have a length along the axis of the nozzle equal to at least one half the diameter of chamber 47. Also, it is critical that the plug be spaced below the open upper end of the body if good aeration is desired in plume 53. It is desirable that grooves 52 be tapered so, as to decrease in cross-sectional area proceeding upwardly through the plug.

It has been found that an ornamental water discharge pattern or plume 53 may be provided with consistency over a wide range of inlet water pressures in a nozzle fabricated of polyvinyl chloride pie having an internal diameter of 2 5/16 inches. In this nozzle, a plug having a thickness of 2 inches along the length of the body is positioned three-quarter inch below the open upper end of the body. Eight grooves, each having a radius of five-sixteenth inch at the lower end of the plug and a radius of one-quarter inch at the upper end of the plug, are formed in the plug. The taper T of these grooves is one-sixteenth inch. The value of angle afor this nozzle is 30. When 85 gallons of water per minute are passed through the nozzle, the discharge pattern produced by the nozzle is 14 feet high and 20 feet in diameter; the back pressure of the nozzle at this flowrate is pounds per square inch.

FIG. 10 shows a nozzle 55 which produces a column of aerated water 56. Nozzle 55 is in accord with the foregoing description of nozzle 45 except that grooves 52 are not tapered and angle a has a value of 0". It is to be noted that the column of aerated water produced by such a noule is of substantially uniform thickness along its entire length above the nozzle to the point where water begins to fall back toward the ground. Plume 56 has been provided in a nozzle constructed of polyvinyl chloride pipe having an internal diameter of 2 5/16 inches. Such a nozzle includes a plug 2 inches thick disposed 1 5/16 inches below the open upper end of the nozzle. Eight grooves each five-sixteenth inch deep and having a radius of one-quarter inch are provided along the length of the plug. When this nozzle is operated to pass water at a rate of 227 gallons per minute, the column of aerated water discharged from the nozzle reaches a height of 86 feet. The water from this column falls to earth or to a fountain pool within a circle 20 feet in diameter. The back pressure of the nozzle at this flowrate is 46 pounds per square inch. The efficiency of this nozzle is considered to be exceptionally high.

FIGS. 11 and 12 show a nozzle 60 producing a two-tier water discharge plume or pattern 61. Nozzle 60 is comprised of the basic structure of noule 45 (body and peripherally grooved plug) to which a central tube 70 has been added. The foregoing description of nozzle 45 is to be kept in mind relative to the following description of noule 60.

Noule 60 includes an elongate tubular body 62 having an open upper end 63 and a lower end defining a liquid inlet opening to an elongate, circularly cylindrical duct chamber 64 defined by the body. The duct chamber, at a location spaced along the body from the open upper end of the body, is spanned and divided by a plug 65 which has its periphery engaged in surface-to-surface contact with the inner walls of the body. Around the circumference of the plug are formed a plurality of generally semicircular grooves 66. The grooves extend between upper and lower surfaces 67 and 68 of the plug generally parallel to the axis of the body within the meaning of the term generally parallel" as developed and explained in the foregoing description of the structure shown in FIGS. 6 and 7. That is, the lengths of grooves 66 are up to about 30 or so skew to the length of the plug. As noted above, nozzle 60 has the feature that it produces a two-tier discharge pattern, and thus angle a in nozzle 60 has a finite value, rather than a value of 0, to cause the water flowing through the grooves to flare outwardly of body 62 after passing over the sharp corner defined by upper end 63 of the body.

The plug is axially bored at 69 to receive an elongate tube 70 which extends axially of the body from an open lower end, communicating with the chamber below the plug, to an open upper end disposed above the open upper end of the body. As with nozzles and 55, it is preferred that plug 65 have a length axially of the body at least about one half the mean transverse dimension of chamber 64 at the location of the plug in the body. Also, the grooves should have lengths at least twice as long as their mean depths. Also, as with the structure shown'in FIGS. 6 and 7, the walls of grooves 66 which are defined by plug 65 make a substantial angle with the inner walls of the body so that the generation of fine sheets of water, which later degenerate into mist or fog, is avoided in noule 60. Further, as in nozzles 45 and 55, the upper surface 67 of plug 65, peripherally of the opening of each groove to the surface, is substantially normal to the length of the plug and to the grooves, notwithstanding that the grooves preferably are skew to the length of the plug, and makes sharp comers with the walls of the grooves. As with the structure shown in FIGS. 6 and 7, the grooves present in nozzle 60 may be tapered between their opposite ends. The spacing between corresponding locations of adjacent grooves circumferentially of the plug is at least as great as one of the grooves, as is the case with the structure shown in FIGS. 6, 7, l3, l5 and 18.

Preferably there are eight grooves 66 formed in the plug about its circumference, The upper ends of the grooves are displaced angularly in the same direction about the axis of the nozzle relative to the lower ends of the grooves. This displacement in the angular relation of the grooves relative to the axis of the nozzle is represented in FIG. 6 by skew angle a. In a development of the peripheral surface of plug 65, grooves 66 are parallel to each other.

The total effective water flow area through plug 65 via grooves 66 and tube 70 is no greater than and preferably is substantially less than the area of chamber 64 below the plug to and including the area of the liquid inlet opening to the nozzle. Accordingly, the extent to which water is aerated by nozzle 60 is determined by the structure of the nozzle itself rather than by structure and a varying aeration characteristic in water presented to the nozzle and to the lower end of the plug within the nozzle.

As shown in FIG. 12, discharge pattern 61 is comprised of a central vertical aerated column of water 71 and an inverted symmetrical cone 72 of aerated water immediately above the nozzle. The central column of water is provided by water emerging from the nozzle through axial tube 70 and, as noted, the conical portion of the water discharge pattern is provided by water emerging through the grooves in plug 65. The nature of cone 72 is to be compared with water discharge plume 53 of nozzle 45 in that cone 72 is of uniform composition, whereas plume 53 is comprised of distinct and readily identifiable separate jets of water.

Water discharge pattern 61 has been produced, over a wide range of applied water pressures, by a nozzle having a body fabricated of polyvinyl chloride pipe, the body having an inner diameter of 3.80 inches. A plug having an axial length of3 a is located 6% inches below the open upper end of the body. Tube 70 is fabricated of l-inch nominal diameter thin-walled brass tubing and has its upper end located 8% inches above the upper surface of the plug. Eight grooves are formed in the circumference of the plug. Each groove has a radius of threeeighth inch; the depth of each groove increases from 0.300 inch at the bottom of the plug to 0.450 inch at the top of the plug. The value of skew angle a for this nozzle is 30. When passing 328 gallons of water per minute at a nozzle back pressure of 17 pounds per square inch, the discharge pattern produced by the nozzle is 21 k feet high and 25 feet in diameter.

An aerating nozzle 75, shown in FIG. 13, includes an elongate hollow body 76 defining a circularly cylindrical inner chamber 77. Like the bodies of nozzles 10, 35, 45, 55 and 60, the lower end of body 76 is open and is internally threaded to define a liquid inlet opening to chamber 77 and to adapt the body for connection to a water supply riser pipe. The chamber opens to the exterior of the nozzle across its entire diameter at an upper end 78 of the body. A plug 79, having a length between parallel opposite end surfaces 80 and 81 at least equal to one-half the diameter of the chamber, is disposed across the chamber between the inner walls of the body at a location spaced below the open upper end of the body. Preferably, the plug is spaced below the upper end of the body a distance at least equal to one-half the maximum transverse dimension of the chamber, i.e., a distance at least equal to one-half the diameter of the chamber. The circumferential walls of the plug are engaged in surface-to-surface contact with the inner walls of the body. A plurality of grooves 82 are formed in the sidewalls of the plug and extend between, and open to the opposite ends of the plug. The grooves form water outlet passages from the portion of the chamber between the plug and the liquid inlet opening to the chamber. The passages are bounded in part by the inner walls of the body. The length- ,to-depth ratios of the grooves should have a value of at least about 2.

Grooves 82 are spaced apart from each other at regular intervals around the circumference of the plug. In Nozzle 75, the grooves are aligned truly, i.e., precisely, parallel to the axis of the chamber and have equal cross-sectional areas at all points along their lengths. Also, the grooves have semicircular cross-sectional configurations. The total cross-sectional area provided by the grooves is not greater than and preferably is substantially less than the cross-sectional area of the chamber between the plug and the open upper end of the body.

Nozzle 75 is in accord with the foregoing description of nozzles 45, 55 and 60 in that the walls of grooves 82 which are defined by plug 79 make substantial angles with the walls of the body rather than small acute angles within which fine sheets of water may be generated during operation of the nozzle. The upper surface of the plug is substantially normal to the lengths of the plug and the grooves about the upper end of each groove and makes a sharp corner with the groove walls as defined by the plug.

As shown in FIG. 13, the inner walls of the body between the plug and the open upper end of the body are straight.

A bore 83 is formed axially through the plug. A hollow tube 84 is fitted into the lower end of the bore sufficiently tightly that water supplied under pressure to the chamber below the plug cannot pass through the bore between the plug and the tube; this same condition of snugness also exists between tube 70 and plug 65 in nozzle 60. Preferably, as shown in FIG. 13, the tube has an open upper end lying in the plane of the upper end of the plug. The tube extends downwardly from the plug into the chamber to a T-joint where the tube branches into oppositely extending lateral extensions 86. The lateral extensions of the tube pass through diametrically opposed apertures 87 in the body below the plug. The extensions terminate in open outer ends 88 exteriorly of the body. The apertures form a Iiquidtight seal with the outer surfaces of the tube extensions.

When water is supplied under pressure to a vertically oriented nozzle '75 through the lower end of the nozzle, the nozzle operates to produce an aerated column or plume 89 of water as shown in FIG. 14. Column 89 is similar to water column 56 produced by nozzle 55, but differs from column 56 in that column 89 has a converging rising portion 90. In other words, the several jets of water which issue from grooves 82 converge upon each other above the open upper end of the nozzle; in nozzle 55, however, the several jets which issue from the plug grooves of the nozzle show substantially no convergence above the open upper end of the nozzle body. Nozzle 75, because of the convergence or tapering of the rising column of aerated water which issues from it, is especially use ful in fountains which must be operated in wind because the discharge column produced by this nozzle retains its character better than the discharge column produced by nozzle 55. Column 89, however, is not as highly aerated, and thus not as discernible in daylight as column 56.

Tube 84 may be extended above the surface of plug 79, if desired, without adversely affecting the performance of the nozzle and without departing from the scope of this invention.

An aerating nozzle like that shown in FIG. 13 has been operated successfully over a wide range of supply water pressures to produce the water discharge pattern shown in FIG. 14. This nozzle has a body fabricated of polyvinyl chloride pipe having an inner diameter of 2 /16 inches. A polyvinyl chloride plug 2 inches thick is mounted in the body 1% inches below the upper end of the body. Eight semicircular vertical grooves each having a radius of one-fourth inch and a uniform depth of one-fourth inch, are provided at regular intervals around the circumference of the plug. A length of three-fourth inch thin-walled brass tubing extends from the top of the plug axially through the plug of lateral extensions communicating to the exterior of the body below the plug; the tube extensions are also fabricated of three-fourth inch thin-walled brass tube. The nozzle has a back pressure of 30 pounds per square inch when passing llO gallons of water per minute. The column defined by the discharge from the nozzle reaches a height of 32% feet and falls back to earth within a circle 10 feet in diameter.

Another aerating nozzle according to this invention, shown in FIG. 15, includes an elongate hollow body 96 defining a circularly cylindrical inner chamber 97. The body has an open, internally threaded lower end (not shown, but see the lower end of nozzle 10) which defines a liquid inlet opening to the chamber and which adapts the body for connection to a water supply duct. The chamber opens to the exterior of the nozzle across its entire aerial extent at an open upper end 98 of the body. A plug 99, having a length between parallel opposite end surfaces 100 and 101 at least equal to one half the mean transverse dimension (the diameter) of the chamber, is disposed across the chamber between the inner walls of the body at a location spaced below the open upper end of the body. Preferably, the plug is spaced below the upper end of the body a distance at least equal to one-half the maximum transverse dimension of the chamber. A plurality of substantially identical grooves 102 are formed in the sidewalls of the plug and extend between, and open to the opposite ends of the plug. The grooves are spaced apart uniformly around the circumference of the plug and are truly parallel to the axis of the nozzle. The grooves open to the inner walls of the body and form water outlet passages through the plug.

Preferably the grooves have equal cross-sectional areas at all locations along their lengths. Also, it is preferred that the grooves be at least twice as long as they are deep. The grooves of nozzle 95 have semicircular crosssectional configurations. As with nozzle 75, the total cross-sectional area of the grooves is not greater than and preferably is substantially less than the area of the chamber below the plug to and including the nozzle inlet opening. Nozzle 95 includes eight grooves 102 each of which has plug-defined walls which make substantial intersecting walls with the inner walls of the body. Also, the upper surface of the plug, around each groove, is substantially normal to the lengths of the grooves and makes a sharp angle, preferably a right angle, with the groove walls.

As shown in FIG. 15, the inner walls of the body above the plug are straight, i.e., parallel to the axis of the body.

A cavity 103 is formed in plug 99 centrally of the body. The cavity has a closed upper end, but communicates with plug lower surface 101. The upper end of the hollow tube 104 is received in the plug adjacent the lower surface of the plug so that the cavity and the interior of the tube are in communication with each other. The connection between the upper end of the tube and the plug provides an air-and liquidtight seal around the tube. The tube has a lower closed end 105 spaced below the plug.

A compressed air duct 106 extends from communication with tube 104 adjacent the lower end of the tube through body 96 below the plug into connection with a compressed air conduit 107 outside the nozzle. It is preferred that conduit 107 be provided by rigid metal or plastic tubing rather than by a flexible hose. Duct 166 is sealed around its exterior to the nozzle body. The compressed air conduit is connected to the outlet of an air compressor 108 via a valve 109 having an actuating or control lever 110. The valve is of the quick-open, quick-close type so that sharply defined pulses of compressed air may be applied to cavity 103 upon cyclic operation of the valve.

Cavity I03 is connected to each groove 102 via a plurality of compressed air passages 111. Each passage connects with its respective groove at about or above the midlength of the groove through the plug. Each passage extends upwardly from the cavity to its respective groove, and preferably makes an angle of about 45 with the axis of the body.

When nozzle 95 is vertically oriented above a water supply duct to which the nozzle is connected, the nozzle produces a lill vertical column of aerated water similar to column 56 produced by nozzle 55 (see FIG. When no compressed air is supplied to cavity 103 via duct 107, nozzle 95 is functionally similar nozzle 55 and produces a plume of water similar to the plume produced by a similarly sized nozzle 55 operated at the same water flowrate. When compressed air is supplied to nozzle 95, however, by operation of valve 109 to operatively connect the compressor to the nozzle, the height of the column of water above the nozzle increases significantly. The introduction of the compressed air into the water outlet passages defined by grooves 102 substantially increases the exit velocity of the water from the passages. The introduction of the air into the water outlet passages also increases the aeration of the water emerging from the nozzle. The height change of the water column produced by nozzle 95 follows substantially immediately the opening or closing of valve 109; the more rapidly the valve is opened or closed, the more sharply defined the change in water column height.

Nozzle 95 may be operated to produce a novel shell burst or skyrocket water discharge pattern shown in FIG. 16. The shell burst pattern is produced by passing water through the nozzle and simultaneously injecting air into the nozzle water outlet passages by opening valve 109 to establish the higher column of water producible by the nozzle. Thereafter, when desired, the valve is closed sharply, either manually or by some suitable mechanism (not shown) which forms no part of the present invention, to substantially instantaneously terminate the injection of compressed air into the water outlet passages. The water which has emerged from the water outlet passages has sufficient kinetic energy that it moves, or at least tends to move, to the height of the higher air-augmented column of water. The water passing through the passage as and after air injection is terminated has a kinetic energy attributable only to the nozzle geometry and the pressure of the water in the main or duct to which the nozzle is connected. Accordingly, the height of the water column above the nozzle is substantially instantaneously reduced to the height of the lower column producible by the nozzle. 1f the water column height is reduced sufficiently rapidly, the rising water which lies between the plug and the top of the air-augmented column continues to rise and defines a quantity of water in midair over the decreased column. This quantity of water tends to coalesce and fall back toward the nozzle as a single body of water. The production of this body of water is critical to the ultimate production of a sharply defined shell burst pattern, and, thus, it is important that valve 109 be closed as quickly as possible.

Before the coalesced body of water, left in midair over the nozzle when the air injection to the water outlet passages is terminated, has fallen below the top of the lower column of water, valve 109 is opened as rapidly as possible to cause the column of water emerging from the nozzle to rise substantially instantaneously to its former height. The top of the rapidly rising column of water forcefully meets the falling coalesced body of water and shatters the body of water. Water drops produced by this impact radiate in all directions from the point of impact to produce shell burst water discharge pattern 115. The faster the column of water rises to meet the falling body of water, the more sharply defined is the shell burst effect. It is therefore important that the valve 109 be opened as rapidly as possible when air-injection is resumed.

The shellburst pattern may be reproduced at any time desired merely by rapidly closing and reopening valve 100 after a delay lasting less than but approaching the time required for water to fall a distance equal to the difference between the higher and lower water column heights.

The shellburst effect could be provided by rapidly closing and opening a valve in the water pipe to which nozzle 95 is connected. Such a practice, however, is extremely undesirable because of the hammer effect produced by a rapidly started or rapidly stopped quantity of water. Such a practice would rapidly cause the water pipe or the valve, or both, to rupture, and would also damage the nozzle. Air, on the other hand, is

compressible and does not produce such hammering effects. The compressibility of the air, however, works against the generation of sharply defined pulses of compressed air in the water outlet passages of the nozzle; for this reason, it is preferred that duct 107 be essentially rigid between the valve and the nozzle, and the that the valve be located as close to the nozzle as is practicable.

Shell burst discharge patterns have been produced at will in a nozzle in accord with the foregoing description. The nozzle body has an inner diameter of 3.800 inches. Plug 99 in this nozzle is 2 inches thick and is disposed 1.950 inches below the upper end of the body. The plug defines around its circumference eight vertical semicircular grooves three-eighth inch deep and three-eighth inch in radius. The air passages from cavity 103 to the grooves are one-fourth inch in diameter. This nozzle has a back pressure of 12 pounds-per square inch when passing water at a rate of l gallons per minute. The nozzle, when valve 109 is closed, produces a column of water 20 feet high. When valve 109 is opened to supply compressed air at 60 pounds per square inch gage pressure to the nozzles, the height of the column of water increases to 32 feet.

Shellburst patterns have also been produced at will in a nozzle wherein the body has an inner diameter of 2 5/l6 inches, the plug is 2 inches thick and is disposed 1.950 inches below the top of the body, the plug defines around its circumference eight vertical grooves one-fourth inch deep and one-fourth inch in radius, and the air passages to the grooves are threesixteenth inch in diameter. This nozzle shows a back pressure of 20 pounds per square inch when water flow through the nozzle is 110 gallons per minute. The height of the lower column of water produced by this water flowrate is 25% feet. When air at a pressure of 60 p.s.i.g. is supplied to the nozzle, the height of the discharged water column increases to 48% feet.

As shown in FIG. 17, nozzle 95 may be disposed at a desired angle to a plumb line and operated in a manner similar to the operation which produces shellburst pattern to produce a serpentine discharge pattern 1 16.

Nozzle 120, shown in FIG. 18, is similar to nozzle 95 in all respects except that the upper end portion of body 121 above plug 99 defines a reducing bell portion 122. At the same height above the plug as body end 98 of nozzle 95, the inner surfaces of the body of nozzle are curved concave inwardly toward the nozzle axis, as at 123, and then recurved convexly, as at 124, away from the nozzle axis to an open upper end 125 of the body defining a nozzle outlet opening 126. Immediately adjacent to the top end of the body, the inner surfaces of the body define a circular cylinder. Preferably, if water aeration is to be maintained, the area of opening 126 is no less than the total cross-sectional area of grooves 102. Nozzle 120 has the feature that the difference between the heights of air-augmented and nonaugmented water discharge columns produced by it is greater than in nozzle 95. For example, in a nozzle 120 wherein the body has a nominal diameter of 2% inches at plug 99 and the nominal diameter of opening 126 is 2 inches, the height of the air-aug' mented water column is approximately 10 times the height of the water column when no air is applied to the nozzle.

From the foregoing it is apparent that this invention provides a number of novel, highly useful water discharge nozzles. These nozzles are particularly useful in ornamental fountain arrangements, but some of these nozzles may be used in other applications as desired. For example, nozzle 95 may be used as a fire nozzle if desired. Each of the nozzles described above produces a high degree of aeration in the liquid passing through it without relying upon any moving parts or critically sized openings to accomplish this aeration. Preferably, the nozzles are fabricated entirely from polyvinyl chloride or some similar plastic; thus these nozzles are highly resistant to the effects of water erosion and have long life expectancies under adverse conditions. The nozzles have in common the feature that the water discharge patterns produced by the nozzles are remarkably free of mist, fog, or fine spray.

In the foregoing description, specific geometrical arrangements and dimensional relationships, and even specific dimensions have been set forth merely for the purposes of example and explanation of this invention; only in certain instances have specified features of the nozzles been stated to be critical. Accordingly, it will be apparent to those skilled in the art, that modifications and alterations in the above-described nozzles may be made without departing from the scope of this invention. As noted above, it will also be apparent to those skilled in the pertinent art that features of one described nozzle may be applied to another described noule without departing from the teachings of the invention, especially where a characteristic of the one nozzle is desired in the other.

lclaim:

l. A liquid discharge nozzle for discharging a stream of liquid generally upwardly therefrom comprising an elongate straight body having opposite open ends defining a duct therethrough between a liquid inlet opening defined across an open lower end of the body and a liquid outlet opening defined across the other open upper end of the body; and a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the upper end of the body and secured from movement along the length of the body; the plug being engaged around its periphery with the inner walls of the duct; the plug having liquid flow passage means therethrough defined by a plurality of grooves formed in the sidewalls of the plug tapered between the opposite ends of the plug and communicating between the opposite ends of the plug; a line between the opposite ends of each groove being skew to the length of the plug within an angle not exceeding about 30; the ends of the grooves at opposite ends of the plug being arranged in sub stantially identical patterns; the grooves and the inner walls of the body cooperating to define a corresponding plurality of liquid outlet p..ssages which have an aggregate cross-sectional area, at least adjacent the upper end of the body, substantially less the than the cross-sectional area of the duct at the location of the plug in the duct; the surface of the plug adjacent the upper end of the body being substantially normal to the elongate extent of the plug peripherally of the opening of each groove to said surface.

2. A nozzle according to claim 1, wherein the grooves decrease regularly in cross-sectional area from the ends thereof adjacent to the lower end of the body to the ends thereof open to the upper end of the body.

3. A nozzle according to claim 1 wherein the grooves are tapered so as to have less cross-sectional area toward said upper end of the body than at the ends of the grooves disposed toward the lower end of the body.

4. A noule according to claim 1 wherein, the grooves are spaced apart from each other a distance at least equal to the width of the grooves circumferentially of the plug.

5. A nozzle according to claim 4 wherein the ends of the grooves open to said plug surface are displaced uniformly about the circumference of the plug relative to the opposite ends of the grooves.

6. A nozzle according to claim I, wherein the grooves constitute the only liquid flow passages communicating between the opposite ends of the plug.

7. A fountain nozzle for discharging a stream of water generally upwardly therefrom comprising an elongate straight body having opposite open ends defining a duct therethrough between a liquid inlet opening defined across an open lower end of the body and a liquid outlet opening defined across the other open upper end of the body; and a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the upper end of the body and secured from movement along the length of the body; the plug being engaged around its periphery with the inner walls of the duct at a location along the body having an effective cross-sectional area not substan tially greater than that of the liquid inlet opening; the plug definin liquid flow passage means therethrough comprised of a plura ity of grooves formed in the sidewalls of the plug at spaced locations around the circumference of the plug. the grooves having sidewalls which intersect the plug sidewalls at a substantial angle, the plug sidewalls between adjacent grooves being engaged in surface-to-surface contact with the duct walls for a distance circumfcrentially of the plug at least equal to substantially the width of one of the adjacent grooves, the grooves being disposed at skew angles to the elongate extent of the plug and communicating between the opposite ends of the plug; the passage means having a total cross-sectional area, at least adjacent the upper end of the body, substantially less than the cross-sectional area of the duct at the location of the plug in the duct; the surface of the plug adjacent the upper end of the body being substantially normal to the elongate extent of the plug peripherally of the opening of each groove to said surface and making a sharp comer in cooperation with the walls of each groove defined by the plug.

8. A liquid discharge nozzle for discharging liquid generally upwardly therefrom comprising an elongate straight body defining a duct therethrough between a lower liquid inlet opening defined across an open lower end of the body and an upper liquid outlet opening defined across an open upper end of the body, a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the duct outlet opening, the duct inlet opening having an area at least as great as the effective crosssectional area of the duct at the location of the plug along the duct, the plug defining liquid flow passage means therethrough comprised of a plurality of grooves formed in the sidewalls of the plug at spaced locations around the circumference of the plug, each groove communicating between opposite ends of the plug, the grooves having sidewalls which intersect the plug sidewalls at a substantial angle, the plug sidewalls between adjacent grooves being engaged in surfaceto-surface contact with the duct walls for a distance circumferentially of the plug at least equal to substantially the width of one of the adjacent grooves, a line between the opposite ends of each groove being oriented relative to the length of the plug within an angle of from 0 to about 30, the ends of the grooves at one end of the plug being spaced apart relative to each other according to substantially the same pattern as are the other ends of the grooves at the other end of the plug, the passage means having a total cross-sectional area at least adjacent the outlet end of the body substantially less than the cross-sectional area of the duct at the location of the plug in the duct, the surface of the plug adjacent the outlet end of the body around the opening of each of the grooves thereto being substantially normal to the length of the plug and defining a sharp corner in cooperation with the walls of each groove defined by the plug.

9. A nozzle according to claim 8 wherein the nozzle is de void of structure spanning the duct between the plug and the outlet end of the duct.

10. A nozzle according to claim 8 wherein the plug has a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct.

11. A noule according the claim 8 wherein the grooves each have a length between opposite ends of the plug at least twice the maximum transverse dimension thereof.

12. A nozzle according to claim 8 wherein the duct has the configuration of a circular cylinder, and the grooves are spaced uniformly about the axis of the cylinder.

' 22;;23 UNI'IED s'l'A'lics PATENT OFFICE CER'IIFICA'IE OF CORRECTION Patent No. 3 558 ,053 Dated January 26 197].

Inventor(s) John O. Hruby, Jr

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 20, for "contract" read --contact--;

line 43, delete "31".

Column 3, line 64, delete "then".

Column 4, line 24, after "the" read --length of the--;

line 46, for "dawn" read --drawn--; line 54, after "The" read --result--.

Column 5, line 67, delete "by".

Column 6 line 24, after "plug" read --a distance at least equal to the width, circumferentially of the lug,-;

line 39, delete 'i".

Column 7 line 4, for "pie" read --pipe- Column 8, line 44, for read --inches--.

Column 10, line 1, for "of" read --to-.

Column 11, line 4, after "similar" read --to-.

Column 12, line 20, for "nozzles" read --nozzle--.

Column 13, line 45, for "adjacent" read --open--; line 46, for "open" read --adjacent--.

Signed and sealed this H th day of December 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'ITSCHALK Attesting Officer Acting Commissioner of Patents 

1. A liquid discharge nozzle for discharging a stream of liquid generally upwardly therefrom comprising an elongate straight body having opposite open ends defining a duct therethrough between a liquid inlet opening defined across an open lower end of the body and a liquid outlet opening defined across the other open upper end of the body; and a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the upper end of the body and secured from movement along the length of the body; the plug being engaged around its periphery with the inner walls of the duct; the plug having liquid flow passage means therethrough defined by a plurality of grooves formed in the sidewalls of the plug tapered between the opposite ends of the plug and communicating between the opposite ends of the plug; a line between the opposite ends of each groove being skew to the length of the plug within an angle not exceeding about 30*; the ends of the grooves at opposite ends of the plug being arranged in substantially identical patterns; the grooves and the inner walls of the body cooperating to define a corresponding plurality of liquid outlet passages which have an aggregate cross-sectional area, at least adjacent the upper end of the body, substantially less the than the cross-sectional area of the duct at the location of the plug in the duct; the surface of the plug adjacent the upper end of the body being substantially normal to the elongate extent of the plug peripherally of the opening of each groove to said surface.
 2. A nozzle according to claim 1, wherein the grooves decrease regularly in cross-sectional area from the ends thereof adjacent to the lower end of the body to the ends thereof open to the upper end of the body.
 3. A nozzle according to claim 1 wherein the grooves are tapered so as to have less cross-sectional area toward said upper end of the body than at the ends of the grooves disPosed toward the lower end of the body.
 4. A nozzle according to claim 1 wherein, the grooves are spaced apart from each other a distance at least equal to the width of the grooves circumferentially of the plug.
 5. A nozzle according to claim 4 wherein the ends of the grooves open to said plug surface are displaced uniformly about the circumference of the plug relative to the opposite ends of the grooves.
 6. A nozzle according to claim 1, wherein the grooves constitute the only liquid flow passages communicating between the opposite ends of the plug.
 7. A fountain nozzle for discharging a stream of water generally upwardly therefrom comprising an elongate straight body having opposite open ends defining a duct therethrough between a liquid inlet opening defined across an open lower end of the body and a liquid outlet opening defined across the other open upper end of the body; and a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the upper end of the body and secured from movement along the length of the body; the plug being engaged around its periphery with the inner walls of the duct at a location along the body having an effective cross-sectional area not substantially greater than that of the liquid inlet opening; the plug defining liquid flow passage means therethrough comprised of a plurality of grooves formed in the sidewalls of the plug at spaced locations around the circumference of the plug, the grooves having sidewalls which intersect the plug sidewalls at a substantial angle, the plug sidewalls between adjacent grooves being engaged in surface-to-surface contact with the duct walls for a distance circumferentially of the plug at least equal to substantially the width of one of the adjacent grooves, the grooves being disposed at skew angles to the elongate extent of the plug and communicating between the opposite ends of the plug; the passage means having a total cross-sectional area, at least adjacent the upper end of the body, substantially less than the cross-sectional area of the duct at the location of the plug in the duct; the surface of the plug adjacent the upper end of the body being substantially normal to the elongate extent of the plug peripherally of the opening of each groove to said surface and making a sharp corner in cooperation with the walls of each groove defined by the plug.
 8. A liquid discharge nozzle for discharging liquid generally upwardly therefrom comprising an elongate straight body defining a duct therethrough between a lower liquid inlet opening defined across an open lower end of the body and an upper liquid outlet opening defined across an open upper end of the body, a plug having substantial length between opposite ends thereof relative to the diameter of the duct disposed across the duct adjacent the duct outlet opening, the duct inlet opening having an area at least as great as the effective cross-sectional area of the duct at the location of the plug along the duct, the plug defining liquid flow passage means therethrough comprised of a plurality of grooves formed in the sidewalls of the plug at spaced locations around the circumference of the plug, each groove communicating between opposite ends of the plug, the grooves having sidewalls which intersect the plug sidewalls at a substantial angle, the plug sidewalls between adjacent grooves being engaged in surface-to-surface contact with the duct walls for a distance circumferentially of the plug at least equal to substantially the width of one of the adjacent grooves, a line between the opposite ends of each groove being oriented relative to the length of the plug within an angle of from 0* to about 30*, the ends of the grooves at one end of the plug being spaced apart relative to each other according to substantially the same pattern as are the other ends of the grooves at the other end of the plug, the passage means having a total cross-sectional area at leAst adjacent the outlet end of the body substantially less than the cross-sectional area of the duct at the location of the plug in the duct, the surface of the plug adjacent the outlet end of the body around the opening of each of the grooves thereto being substantially normal to the length of the plug and defining a sharp corner in cooperation with the walls of each groove defined by the plug.
 9. A nozzle according to claim 8 wherein the nozzle is devoid of structure spanning the duct between the plug and the outlet end of the duct.
 10. A nozzle according to claim 8 wherein the plug has a length between the opposite ends thereof greater than about one-half the mean transverse dimension of the duct at the location of the plug along the duct.
 11. A nozzle according the claim 8 wherein the grooves each have a length between opposite ends of the plug at least twice the maximum transverse dimension thereof.
 12. A nozzle according to claim 8 wherein the duct has the configuration of a circular cylinder, and the grooves are spaced uniformly about the axis of the cylinder. 